Hi–Running Photoshop CS on a brand new G5 with 4 GB of ram. Everytime i check preferences there is a different amount of memory available for photoshop (it’s the only app running). One time it will be 1800 mb, a few minutes later it’ll be 1805, a few minutes later it’ll be 1796 mb. It has dropped as low as 1600 mb. Any idea what’s happening here?
Also, how much should be put into the preference box for "maximum used"? I used to put 75% when I had a machine with only 2 GB of ram. Can i put in 100% now?
I’ve looked through the other forums and FAQ’s but haven’t found anything relavent. Any help is appreciated
If you do a search on this forum you’ll find that this has been discussed here very often.
Read the following recent thread, for instance:
Geof Smith "Photoshop CS + Panther crashes" 4/26/04 1:52pm </cgi-bin/webx?14/0>
In OS X the old RAM allocation does not exist any more. The % you define is the maximum percentage of available RAM Photoshop is allowed to grab for itself at any given time. Because OS X allocates RAM dynamically, available memory changes constantly.
Because any application can use no more than 2GB of RAM anyway, if you have 4GB of RAM (or more) you could give it 100%. I’d still go with 90% or 90% anyway, since the theoritecal 2GB limit is really a little bit less than 2GB.
As you’ll see, Photoshop only uses what it needs. It’s not like you are forcing it to set aside an allocation, like we do in OS 9. And see my comment above re the continually changing available RAM.
Ed, the answer is earlier in the thread, where the optimum percentage varies depending on the installed RAM relative to the 2GB-per-application limit. So…
If your Mac has up to 2GB, Photoshop should not be allowed to have more than 65-75%, otherwise Photoshop may compete with OS X for the 2GB.
If your Mac has around 4GB or more, it’s possible to assign Photoshop 100%, because that will equal 100% of its 2GB limit, not all 4GB on the machine. OS X and other apps will still be able to use what’s above Photoshop’s 2GB. I think that’s why Tim can run with Photoshop at 100% on a 4GB Mac and not have problems, while giving Photoshop 100% on a Mac with under 1GB RAM would be a disaster.
The idea that you cannot set Photoshop 8 to use 100% of the dynamically changing available RAM when you have 4GB (or more) of installed RAM is simply rooted in a misunderstanding of what the percentage refers to. If you read the threads to which links have been provided, you’ll be able to read the clear explanation that Chris Cox gave us. It pays to wade through those threads.
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